if (z<0)  z = -z ;

if (d < 0 ) printf ("akar imaginer") ;
else
{	x1 = (-b + sqrt(d))/2.0/a ;
	x2 = (-b - sqrt(d))/2.0/a ;
}

if ( nilai > 9.0 ) printf ("\n Istimewa ") ;
else if  ( nilai > 7.5 ) printf ("\n Baik ") ;
else if  ( nilai > 6.0 ) printf ("\n Cukup ")
else if  ( nilai > 4.5 ) printf ("\n Kurang ") ;
else printf ("\n Tidak memuaskan ") ;
